CN106797572B

CN106797572B - Listen-before-talk for cellular subframe alignment in unlicensed frequency bands

Info

Publication number: CN106797572B
Application number: CN201580055804.4A
Authority: CN
Inventors: A·博卡尔; 权桓俊; C·伊巴尔卡萨斯
Original assignee: Intel IP Corp
Current assignee: Intel Corp
Priority date: 2014-11-06
Filing date: 2015-11-04
Publication date: 2020-10-16
Anticipated expiration: 2035-11-04
Also published as: KR20180052774A; KR102293632B1; EP3216304A4; KR20170060080A; US9326157B1; US20180035303A1; KR101857549B1; EP3869902A1; WO2016073616A1; US9788212B2; CN106797572A; US20160135055A1; JP2017539145A; JP6680778B2; US20160309334A1; EP3216304A1; JP7110262B2; JP2020108171A; EP3216304B1; US10219164B2

Abstract

Disclosed in some examples are systems, machine-readable media, methods, and cellular wireless devices implementing a Listen Before Talk (LBT) access scheme in an unlicensed channel for devices operating according to a cellular wireless protocol. After the LBT access scheme has determined that a channel (defined frequency range) in the unlicensed channel is idle for a particular period of time, the cellular wireless device may utilize a cellular wireless protocol in the unlicensed channel.

Description

Listen-before-talk for cellular subframe alignment in unlicensed frequency bands

Priority requirement

This patent application claims priority to U.S. application serial No. 14/711,278 filed on

day

5 and 13 of 2015, which claims priority to U.S. provisional patent application serial No. 62/076,083 filed on

day

11 and 6 of 2014, both of which are incorporated herein by reference in their entirety.

Technical Field

Embodiments pertain to cellular radio technology. Some embodiments relate to cellular wireless technology operating in unlicensed communication bands.

Copyright notice

A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the patent and trademark office patent file or records, but otherwise reserves all copyright rights whatsoever. The following statements apply to the software and data described below and in the accompanying drawings which form a part of this document: the intel copyright is owned and all rights are reserved.

Background

Cellular wireless technologies typically operate in licensed spectrum. A licensed spectrum is a range of frequencies allocated for use by a particular entity (e.g., a particular wireless carrier). Since the licensed spectrum available is limited and as the demand for cellular wireless services rises, the amount of free spectrum available is limited.

In contrast to licensed spectrum, there are various unlicensed spectrum that allow certain frequencies to be used without the entity obtaining legal approval. These frequencies are shared between devices that wish to use them, and devices using these spectrum have protocols that allow them to share the spectrum with other devices. Typically, these unlicensed spectrum are not licensed primarily for cellular wireless use, and typically, these spectrum are subject to competition or utilization by other devices.

Drawings

In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

Fig. 1 is a timeline of a synchronous listen-before-talk (LBT) method according to some examples of the present disclosure.

Fig. 2A illustrates a slot diagram of symbol aligned slots according to some examples of the present disclosure.

Fig. 2B illustrates a slit diagram of uniformly divided slits according to some examples of the present disclosure.

Fig. 3 illustrates a flow diagram of a method for a first option of LBT listen and back-off, according to some examples of the present disclosure.

Fig. 4 illustrates a flow diagram of a method for a second option of LBT listening and fallback according to some examples of the present disclosure.

Fig. 5 illustrates a flow diagram of a method for a third option of LBT listen and back-off, according to some examples of the present disclosure.

Fig. 6 illustrates a diagram of an expected scheduling of SDLs, according to some examples of the present disclosure.

Fig. 7 illustrates a flow chart of a method of anticipatory scheduling of SDLs, according to some examples of the present disclosure.

Fig. 8 illustrates a diagram of puncturing (puncturing) symbols of a subframe in accordance with some examples of the present disclosure.

Fig. 9 illustrates a flow diagram of a method for a cellular wireless device to puncture symbols in accordance with some examples of the disclosure.

Fig. 10 shows a schematic diagram of a cellular wireless device, in accordance with some examples of the present disclosure.

Fig. 11 illustrates a schematic diagram of a wireless environment, in accordance with some examples of the present disclosure.

Fig. 12 illustrates a block diagram of an example machine on which any one or more of the techniques (e.g., methods) discussed herein may be performed in accordance with some examples of the disclosure.

Detailed Description

As the demand for licensed spectrum for cellular wireless protocols, such as Long Term Evolution (LTE), increases, designers of LTE systems have begun to explore the use of these licensed protocols in unlicensed frequencies. The use of cellular protocols and other licensed protocols in unlicensed frequencies presents some challenges. Unlicensed frequencies may include industrial, scientific, and medical (ISM) bands, such as 2.4GHz, 5GHz, and the like. The unlicensed frequency may be determined by one or more governmental entities (e.g., the Federal Communications Commission (FCC) in the united states).

For example, cellular wireless devices (e.g., base stations or mobile devices such as smart phones) utilize an authorized channel, which ensures that these devices have exclusive use of a particular wireless channel. A "channel" is a (usually, but not always, continuous) segment of frequency used for wireless communication. Thus, these cellular protocols are designed with the assumption that they have exclusive access to the frequencies on which they operate. They are generally concerned with coordinating among other devices participating in the same network. For example, in an LTE system, a base station (eNodeB) typically coordinates transmissions and receptions from one or more User Equipments (UEs) associated with the eNodeB. When planning the transmission and reception of data, the eNodeB typically does not consider other users in other networks. If the cellular wireless network starts transmitting in the unlicensed channel without modification, the cellular wireless device will continuously transmit and receive. This will prevent other devices from utilizing the channel.

In contrast, devices operating in an unlicensed channel consider not only devices operating in a single network (e.g., controlled by a single operator), but also devices operating in many different networks and devices operating using other protocols. For example, devices operating according to a wireless protocol such as the 802.11 standard (Wi-Fi) defined by the Institute of Electrical and Electronics Engineers (IEEE) consider not only devices in their own network (i.e., basic service set-BSS), but also devices in other BSSs, and even devices running other protocols, before determining whether they are able to use the wireless medium.

What is needed, therefore, is a method of adapting a cellular wireless protocol to operate in an unlicensed channel in an efficient manner. Disclosed in some examples are systems, machine-readable media, methods, and cellular wireless devices implementing modifications for operating in unlicensed frequency bands according to cellular wireless protocols. These modifications include implementing a Listen Before Talk (LBT) access scheme for use by the cellular wireless device in the unlicensed channel, optimizing scheduling, and optimizing channel sensing.

As used herein, a "cellular wireless device" is any device that operates according to a cellular wireless protocol. A "cellular radio protocol" is a radio protocol that defines a cellular radio network that is distributed over terrestrial areas called cells, each cell being served by at least one fixed-location transceiver called a cell site or base station. The cell sites are interconnected to provide wireless service over a wide geographic area. Example cellular wireless protocols that may be suitable for transmission in an unlicensed channel include cellular wireless protocols according to one of the following standards: the LTE family of standards promulgated by the third generation partnership project (3GPP), including the LTE advanced (LTE-a) family of standards, the Universal Mobile Telecommunications System (UMTS) family of standards promulgated by the 3GPP, the global system for mobile communications (GSM) family of standards, and the like. The cellular wireless device may be a base station (e.g., a NodeB or eNodeB), or may be a mobile device (e.g., a UE).

In some examples, the cellular wireless device may use the licensed band to control transmissions on the unlicensed band (e.g., obtain Channel State Information (CSI) feedback, schedule on a Physical Downlink Control Channel (PDCCH), etc.).

Example transmissions by a cellular wireless device in an unlicensed channel include transmissions by layer 1, layer 2, layer 3, and other layers that support these cellular protocols, such as one or more of a Physical (PHY) layer, a Medium Access Control (MAC) layer, a Radio Link Control (RLC) layer, a Packet Data Convergence Protocol (PDCP) layer, and a Radio Resource Control (RRC) layer. The channels for transmission in the unlicensed frequencies may include any uplink data channel, uplink control channel, downlink data channel, and downlink control channel. Examples include one or more of a Physical Downlink Shared Channel (PDSCH), a Physical Uplink Shared Channel (PUSCH), a PDCCH, and a Physical Uplink Control Channel (PUCCH).

In some examples, a cellular wireless device, such as a cellular base station (e.g., eNodeB), may provide uplink and downlink capabilities to a cell in a licensed spectrum and also provide Supplemental Downlink (SDL) channels in an unlicensed spectrum. The SDL channel may carry one or more LTE channels, such as PDSCH. LBT techniques may be applied to SDL channels to ensure that the unlicensed channels are free and free of interference. In other examples, for an uplink channel on an unlicensed spectrum, the UE may be a cellular wireless device implementing an LBT mechanism. In some examples, SDL may be scheduled on PDCCH on the primary (licensed) frequency. For example, a UE may be scheduled on the PDCCH on the licensed frequency to receive data on the SDL PDSCH on the unlicensed frequency (i.e., using cross-carrier scheduling).

Aspects of a cellular wireless protocol may be modified in one or more ways, such as those disclosed herein, to operate within unlicensed spectrum. For example, the LBT access scheme may be implemented in a cellular wireless protocol by a cellular wireless device.

LBT, channel sensing and fallback design

In some examples, a cellular wireless device implementing an LBT access mode for unlicensed bands may listen for a channel duration channel listening time (predetermined period of time). The cellular wireless device may consider the channel available for transmission if the channel is idle for a channel listening time.

Fig. 1 shows a timeline 1000 of a cellular wireless device operating synchronously in an unlicensed channel using an LBT mechanism. At step 1010, the transceiver of the cellular wireless device Carrier Senses (CS) the channel in the unlicensed band for a period of W μ s and determines the average power received. If the received power is less than the threshold T dBm, the channel is considered idle. Otherwise, if the received power is greater than the threshold, the channel is considered busy. At step 1020, if the channel is determined to be idle, the transceiver enters a back-off phase. In the back-off phase, the transceiver selects a back-off period. The time period may be chosen randomly from a set of legal values. In some examples, the time period may be a multiple of the LTE symbols. During this back-off, the transceiver listens to the channel. If the channel is busy during this period, the transceiver returns to the carrier sensing phase at step 1010. If the channel is idle, the transceiver proceeds to step 1030. The back-off period of step 1020 may be considered to be a random duration extension of the fixed duration carrier sensing phase of step 1010. The backoff period prevents a large number of wireless devices with the same value for W from all attempting to access the medium at the same time.

During step 1030, the transceiver may transmit a reservation message or signal to reserve the channel until the next subframe boundary of the cellular network, or until the next subframe boundary plus the amount of time required to transmit the next subframe in order to align to the subframe. Example reservation signals may be Wi-Fi request-to-send (RTS) or clear-to-send (CTS). Once the subframe boundary is passed, the transceiver may transmit at step 1040.

For downlink operation on the unlicensed channel, the eNodeB may implement the LBT decision for the LTE network, while on the uplink, the eNodeB may implement the LBT mechanism, but communicate information to the UE that enables the UE to transmit during step 1040.

In the context of cellular wireless networks such as LTE, it is desirable to define how often to sample the channel when carrier sensing or fallback sensing. Sampling the channel too often results in increased manufacturing costs and increased workload on the transceiver. Too low a frequency of sampling the channel may result in the channel being falsely reported as idle and causing collisions.

There are fourteen symbols within the LTE subframe. In some examples, the channel may be sampled once per symbol. However, this level of sample granularity may be too infrequent because each frame is 1 millisecond, while 1 millisecond 1/14 is about 70 microseconds.

In some examples, a smaller sample granularity may be utilized. For example, each symbol may be subdivided into two or more "slots". As used herein, a slot may be defined as a basic unit of granularity of listening to a channel and may be defined with reference to timing information of a cellular radio protocol. For example, each symbol may be divided into four slots. In these examples, the slot does not cross the symbol boundary. This presents a dilemma because in an LTE subframe, the first and eighth symbols are slightly larger, with 2208 samples compared to 2192 samples in the other symbols. In these examples, the slot of the first symbol and the eighth symbol may be 552 samples and the remaining slots may be 548 samples. In other examples, the additional symbols (16) may be partitioned in other ways for the first and eighth symbols. For example, three of the slots of the symbols may be 548 samples, and the remaining slots may be 564 samples. Fig. 2A shows an example slot diagram 2000 of symbol aligned slots. As shown, the slot 2010 for symbol 1 is slightly larger than the

slots

2020 and 2040 for symbol 1 and the remaining symbols 2-14, except for one or more slots in symbol 8 (symbol 8 also contains 2208 samples).

In other examples, rather than dividing the symbols to generate slots, the sub-frame itself may be subdivided into equal, fixed-size slots. In this example, the slot may comprise portions of two consecutive symbols. That is, the slot may cross the symbol boundary. Fig. 2B shows an example slot map 2100 of evenly divided slots. In some examples, the first slot 2110 starts at the beginning of a subframe and the last slot 2120 ends at a subframe end boundary. As can be seen from the figure, the slot may cross a symbol boundary, for example, the slot 2130 of

symbols

1 and 2. In some examples, if N is the number of samples in a slot, since it may be desirable for the slot boundary to coincide with a subframe boundary (which has 30720 samples), N may be chosen such that N is a factor of 307200. Thus, the number of slots can be described by 30720/N. Since each subframe is 1 millisecond (ms) (10) in duration³μ s) and because there are 30720 samples in a subframe, there are 30.72 samples in 1 microsecond. Since the LTE specification defines the minimum listening period for the unlicensed channel as 20 microseconds (μ s), multiplying by 20 results in 614.4 samples within 20 microseconds as the minimum number of samples to listen.

Since the samples are the smallest granularity in LTE, having 0.4 samples may round up (since 614 would produce a listen time of less than 2 microseconds) to at least 615. However, it may be desirable for N to be a factor of 30720, so that all slots fit into the same subframe. One option may be that there are 48 slots in the subframe, calculated to be 640 samples for each slot. Having 640 samples/slot means that each slot is about 20.83 microseconds long, which is slightly above the minimum of 20 microseconds. In other examples, more slots per subframe may be utilized; however, the cellular wireless device may need to listen to more than one slot in order to meet the minimum specified in the LTE specifications.

To implement listen and fall back, three example designs are disclosed herein. These options are applicable to coexistence between cellular wireless protocols (e.g., LTE) and wireless protocols operating on unlicensed channels (e.g., Wi-Fi).

Fig. 3 illustrates a flowchart of a method 3000 for a first option of LBT listening and fallback, according to some examples of the present disclosure. In a first option, a Contention Window (CW) is employed to determine when the channel is clean. At operation 3010, the transceiver of the cellular wireless device may select a random number between 1 and q. In some examples, q is defined as a predetermined value between 4 and 32, which in some cases may be determined by the manufacturer of the cellular wireless device. In other examples, q may change dynamically. At operation 3020, the transceiver of the cellular wireless device may listen to the channel for a period of time that is (or is approximately) CW times a Clear Channel Assessment (CCA) duration (CD) (CD on the order of microseconds). CD may be defined as one or more complete slits. To determine whether the channel is idle, in some examples, the received power of the channel during a particular CD may be compared to a predetermined threshold (e.g., a threshold of-62 dBm). If the power is less than the threshold, the channel may be considered idle during the gap. If the power is above the threshold, the channel may be considered busy during the gap. In some examples, if a single slot is considered busy, the entire cycle may be considered busy. In other examples, an entire CW CD cycle may be considered busy if more than a predetermined amount of slots are considered busy. In further examples, the received power may be sampled at each slot, then averaged over the entire CW CD period, and the average power over that period compared to a threshold. If the average power is above the threshold, the channel may be considered busy. If the average power is below the threshold, the channel may be considered idle.

If the channel is deemed idle, the cellular wireless device may continue with: in operation 3030, the SDL is sent. If the channel is deemed busy, the cellular wireless device may return to operation 3010 and begin anew.

In some examples, this method of detecting that the medium is idle is different from the Wi-Fi carrier sensing method. In Wi-Fi carrier sensing, Wi-Fi devices use both energy detection mechanisms and signal detection mechanisms. If the Wi-Fi device detects a Wi-Fi signal using a signal detection mechanism, the Wi-Fi device assumes that the channel is occupied. In some examples, the LBT methods disclosed herein use only energy detection mechanisms, and not Wi-Fi signal detection mechanisms. Note that in fig. 3, CD is the duration of the Clean Channel Assessment (CCA) (in mus), which may be the slot duration or a multiple thereof.

Fig. 4 shows a flow diagram of a method 4000 for listening and fallback a second option of an LBT implementation. In operation 4010, the transceiver listens to the channel for W μ s. W may be a time period equal to one or more slots. In operation 4020, a comparison is made, and if the received power is higher than a threshold T for a W period, the transceiver returns to operation 4010. If the received power is below the threshold T for the W period of time, the transceiver proceeds to operation 4030. If W contains more than a single slot, the power comparison may be the average power across all slots, or the comparison at operation 4020 may be per slot. In the per slot case, if more than a predetermined number (e.g., one or more) slots fail in the comparison (e.g., the power level is greater than a threshold), the comparison at operation 4020 fails and flow returns to operation 4010.

In operation 4030, the transceiver may generate a random number CW between 1 and q, where q (as previously described) is a number between 4 and 32. At operation 4040, CW may be decremented (e.g., CW ═ CW-1). In operation 4050, a comparison is made to determine whether CW is less than or equal to zero. If the CW is less than or equal to zero, the channel is clean and the transceiver may transmit at operation 4060. If CW >0, the transceiver may listen to the channel for the slot period in operation 4070. At operation 4080, a comparison is made and if the observed power level is less than a threshold, a determination is made that the channel is idle for the gap and operation proceeds to 4040 where CW is decremented again. If the channel is not idle, operation returns to 4010. Note that in fig. 4, CD is the duration of the Clean Channel Assessment (CCA) (in mus), which may be the slot duration or a multiple thereof.

Fig. 5 illustrates a flow diagram of a method for a third option of LBT listen and back-off, according to some examples of the present disclosure. At operation 5010, the transceiver listens to the channel for W μ s. W may be a time period equal to one or more slots. In operation 5020, a comparison is made and if the received power is above the threshold T for a W period of time, the transceiver returns to operation 5010. If the received power is below the threshold T for the W period of time, the transceiver proceeds to operation 5030. If W contains more than a single slot, the power comparison may be the average power across all slots, or the comparison at operation 5020 may be per slot. In the per slot case, if more than a predetermined number (e.g., one or more) slots fail in the comparison (e.g., the power level is greater than the threshold), the comparison at operation 5020 fails and flow returns to operation 5010.

In operation 5030, the transceiver may determine whether the channel is congested. For example, if the transceiver has to listen to the channel for W μ s more than a predetermined number of times at operation 5010, the transceiver may determine that the channel is congested. In other examples, the transceiver may determine channel congestion based on errors in previous transmissions (e.g., utilizing a Transport Block Error (TBE) level). If the TBE is above a predetermined threshold, the channel may be determined to be congested.

At operation 5050, if the channel is congested, the parameter CWT may be set to the maximum of: finally twice the CWT and the maximum Contention Window (CWMAX). CWT, CWMIN, and CWMAX may be predefined; for example, CWT may be initially 1, CWMIN may be 1, and CWMAX may be 1024. At operation 5040, if the channel is not congested, the CWT may be set to 1.

In operation 5070, the transceiver may generate a random number CW by adding the value D to a random number chosen between CMIN and CWT. D may be equal to the time required to transmit one or more LTE symbols for the number of slots. At operation 5080, CW may be decremented by D (e.g., CW ═ CW-D). At operation 5090, a comparison is made to determine whether CW is less than or equal to zero. If CW is less than or equal to zero, the channel is clean and the transceiver may transmit in operation 5100. If CW >0, the transceiver may listen to the channel for a D period of time (which may be one or more slots) in operation 5110. If it is determined in operation 5120 that the channel is idle, operation proceeds to operation 5080 where the CW is decremented again. If the channel is not idle, operation returns to operation 5010. It may be determined that the channel is idle as described in options 1 and 2 (i.e., the power observed in each slot may be below a threshold, the average power observed in each slot may be below a threshold, or a predetermined number of slots in a CD cycle may be below a threshold).

Scheduling optimization

In some examples, SDL may be implemented using a control channel on a grant channel (i.e., a primary channel). For example, in LTE, SDL may be implemented with PDCCH on the grant channel. The PDCCH is typically carried on the first three symbols of the current subframe and schedules the current subframe. If the backoff period is completed before the start of the next subframe, the eNodeB may reserve the channel by sending a channel reservation message (e.g., a request-to-send-RTS message, or a clear-to-send-CTS message) on the unlicensed channel and schedule the SDL using the PDCCH of the next subframe. If the backoff period ends during the PDCCH transmission of the next subframe, the SDL may be scheduled according to other schedules and the bandwidth of the PDCCH. If the backoff period ends before the SDL can be scheduled on the PDCCH of the grant channel, then the SDL transmission opportunity may be wasted.

In some examples, the eNodeB may schedule the SDL even if the backoff period will not end until after the subframe begins. For example, the eNodeB may predict that the backoff period may be successfully completed (the channel remains idle for the entire period) and may schedule the remainder of the SDL persistent subframes after scheduling completion of the backoff procedure. For example, if the fallback procedure is to be completed halfway through a subframe, the eNodeB may schedule half of the subframe in anticipation that the fallback procedure may be successfully completed.

In some examples, predicting that the fallback period may be successfully completed may include: it is assumed that the backoff period is successfully completed. In some examples, the past history of the channel may be used to predict that the backoff period will be successfully completed. In these examples, if the eNodeB has successfully completed the backoff procedure in the past on the channel for more than a threshold percentage of time, the eNodeB may predict that the backoff procedure for this time may be successful. Other algorithms may include consideration of one or more of the following factors: access time, channel history, past error rate, etc. An example algorithm may utilize if-then statements that compare these factors to predetermined thresholds.

In some examples, the fallback overlap may be limited to the first three symbols of the current subframe (where PDCCH is typically sent). Thus, if backoff is to be completed in the first three symbols of the current subframe, the eNodeB may schedule the SDL PDSCH. Otherwise, if there is no scheduling completion backoff in the first three symbols of the current subframe, the eNodeB will not schedule the SDL PDSCH in the current subframe.

In the case where the eNodeB expects to schedule the SDL PDSCH, the UE receives data on the SDL if the backoff period is successfully completed and the eNodeB is able to send the SDL. If the channel becomes busy before the end of the backoff period and the eNodeB does not gain access to the unlicensed channel, the UE may not be aware of this and will receive invalid data (e.g., noise). The UE will not be able to successfully decode PDSCH on SDL. In the ideal case, the UE would simply drop PDSCH on SDL for that subframe. The UE considers it to be missing data sent to it and will therefore request retransmission of the missing data using a hybrid automatic repeat request (HARQ) function. In this case, the eNodeB may ignore any HARQ requests for the data and may indicate to the UE to remove the data from its HARQ buffer. For example, a new Downlink Control Information (DCI) format may be defined to carry an indication that the SDL is not actually sent on the grant-free channel. Alternatively, in some examples, a new physical signal or channel may be defined to carry the new indication message.

Turning now to fig. 6, a diagram 6000 of the expected scheduling of SDLs is shown. LBT and backoff start on symbol 6010 of subframe 6020. If backoff is predicted to be completed before symbol 6030 (the third symbol of subframe 26040), the eNodeB may schedule SDL on subframe 26040. For example, the eNodeB may schedule the UE to receive data on symbol 6050.

Turning now to fig. 7, a flow chart of a method 7000 of prospective scheduling of SDL is shown. At operation 7010, a cellular wireless device (e.g., eNodeB) may participate in LBT and fallback procedures (e.g., fig. 3-5). At operation 7020, the cellular wireless device predicts whether LBT and fallback procedures will be completed in time. In some examples, this is simply assuming that the back-off procedure does not return to a busy channel and determining whether there is sufficient time to schedule any portion of the SDL. For example, if the backoff procedure is to be completed within the first three symbols of a particular subframe, the subframe may be scheduled. In other examples, other criteria may be used, such as past channel usage history or past LBT and backoff success rates.

If at operation 7030, the rollback is not predicted to be completed on time, flow proceeds to operation 7040. At operation 7040, once the backoff procedure is complete, the channel may be reserved until a subframe can be scheduled and transmitted on the SDL. If the fallback procedure is scheduled to be completed on time, at operation 7050, a subframe may be scheduled on the PDCCH of the grant channel as appropriate. At operation 7070, the cellular wireless device may determine whether LBT and backoff are completed in time. If so, the cellular wireless device may normally send the SDL on the unlicensed channel at operation 7080. If not, the cellular wireless device may ignore any HARQ retransmission requests for the unsent SDL subframes from any UEs scheduled on the SDL in operation 7090. In operation 7100, the cellular wireless device may send a message to the UE scheduled on SDL to clear its HARQ buffer and terminate retransmission attempts for the data.

Channel sensing optimization

In some examples, to transmit multiple subframes, the cellular wireless device may perform listening and backoff with one or more symbols in the current subframe in which no data is transmitted in order to meet the requirement to transmit another subframe. The symbols of the current subframe for performing the listening and backoff operations are "punctured". In some examples, the last K symbols of the current frame are punctured. In some examples, K-2. In some examples, each subframe may be punctured by K symbols. In other examples, every L subframes may be punctured (e.g., every second subframe, or every third subframe, etc.). K may be static (i.e., K symbols may be punctured every lth subframe), but in some examples K may change such that K in one subframe is different from K in another subframe.

A UE associated with an eNodeB may be informed of symbol puncturing in order to discard any received data during these symbols. The notification to the UE may include the precise location of the punctured symbol. An example notification may include a new DCI. The DCI may include a bitmap of B (up to 14) bits indicating the positions of punctured symbols in a subframe. In other examples, DCI may be avoided if a transceiver on a cellular wireless device uses significantly higher redundant MCS (with lower coding rate) transmissions to counteract puncturing.

Turning now to fig. 8, a diagram 8000 of puncturing the last two

symbols

8020 and 8030 of a subframe is shown. The three symbols 8040 of subframe 1 are occupied by Wi-Fi traffic or are idle. Three symbols 8050 are listen and backoff, and eight symbols 8060 are reserved by the cellular wireless device before the beginning of subframe 2. Once subframe 2 begins, the cellular wireless device may transmit SDL PDSCH 8070. The

symbols

8030 and 8020 are punctured to start listening and back-off for the next subframe (not shown).

In some examples, the implemented fallback may be any of the aforementioned methods. In some examples, channel sensing optimization may be combined with scheduling optimization. In any case, all of the various options for channel sensing and backoff are compatible and may be used with either or both of channel sensing optimization and scheduling optimization.

Turning now to fig. 9, a method 9000 of a cellular wireless device puncturing K symbols is shown, according to some examples. In operation 9010, the cellular wireless device may determine that another subframe is expected for SDL transmission. For example, an eNodeB may have additional data for one or more UEs. In operation 9020, the eNodeB may determine K. K may be predetermined or may be variable. In operation 9030, puncturing parameters may be communicated to one or more UEs scheduled on a current subframe. The puncturing parameters may include symbols to be punctured or one or more pieces of information (e.g., K) that allow the UE to infer the symbols to be punctured. In operation 9040, the cellular wireless device may perform LBT and backoff in punctured symbols of the current subframe.

Turning now to fig. 10, a schematic diagram of a cellular wireless device 10000 is shown, according to some examples. Cellular wireless device 10000 can be any device capable of communicating using an authorized cellular protocol. The cellular wireless device 10000 may be a nodeB, eNodeB, UE, Base Transceiver Station (BTS), Wi-Fi access point, cellular phone, smartphone, desktop computer, laptop computer, medical device (e.g., heart rate monitor, blood pressure monitor, etc.), wearable device (e.g., computing glasses, smart watch), etc.

The cellular wireless device 10000 can include a first wireless transceiver 10030, a second wireless transceiver 10040, and control circuitry 10020 for controlling the first wireless transceiver and the second wireless transceiver. The first wireless transceiver 10030 may operate on an unlicensed channel and, in some examples, implement a wireless protocol that is not a cellular wireless protocol. In some examples, the first wireless transceiver 10030 can implement a wireless protocol that operates in an unlicensed channel, such as an IEEE802.11 wireless protocol, a Bluetooth Low Energy (BLE) wireless protocol, a Zigbee wireless protocol, and the like. In some examples, the first wireless transceiver 10030 may determine whether the unlicensed channel is occupied by other traffic. In some examples, the first transceiver 10030 may detect a power level on the unlicensed channel and, if the average power level is below a particular threshold for a predetermined period of time, the control circuitry 10020 may determine that the channel is not occupied using one or more of the methods of fig. 3-5.

Once a channel is deemed unoccupied, the control circuit 10020 may control a backoff process. Control circuit 10020 may implement the operations of fig. 3-5 in cooperation with first transceiver 10030, such as selecting a random contention window, decrementing the contention window, detecting a channel duration of W μ β using first transceiver 10030, determining whether a back-off period is over, or if activity is detected on the channel during the back-off period, signaling first transceiver 10030 to again determine whether the medium is idle by detecting a power level on the unlicensed channel for a channel listening period. Once control circuit 10020 and first transceiver 10030 have determined that the channel is again idle, control circuit 10020 will restart and implement the backoff process again.

Control circuit 10020 may also implement scheduling optimizations and channel sensing optimizations. For example, control circuitry 10020 may predict whether LBT and backoff will complete in time to schedule a subframe. If LBT/backoff is not predicted to be completed in time, the control circuit 10020 may instruct the first transceiver 10030 or the second transceiver 10040 to: for the next available subframe, a reservation message is sent once LBT and backoff are complete. If LBT/fallback is predicted to be completed in time to transmit the SDLPDSCH in the current subframe, the control circuitry will schedule one or more UEs on the SDL PDSCH via the PDCCH transmitted by the second transceiver 10040. If the UE is scheduled but the LBT/fallback procedure is not successfully completed, the control circuitry may ignore any HARQ transmission associated with the subframe. The control circuitry may also instruct any receivers (e.g., UEs) to remove these items from their HARQ queues via the second transceiver 10040 or the first transceiver 10030 (e.g., through a grant channel or a grant-free channel) so they will no longer request retransmissions.

Control circuit 10020 may also implement one or more channel sensing optimizations. The control circuitry 10020 can determine K and L and communicate with any receiver (e.g., a UE) regarding the puncturing parameters via the second transceiver 10040 or the first transceiver 10030 (e.g., over a grant channel or an unlicensed channel). Further, control circuitry 10020 may implement the puncturing via the first transceiver.

The second wireless transceiver 10040 can implement a cellular wireless protocol and can generally transmit over a licensed frequency. Example cellular wireless protocols may include the Long Term Evolution (LTE) family of standards promulgated by the third generation partnership project (3GPP), the Universal Mobile Telecommunications (UMTS) promulgated by the 3GPP, the Institute of Electrical and Electronics Engineers (IEEE)802.16 standard known as Worldwide Interoperability for Microwave Access (WiMAX), and so forth. The second transceiver 10040 may provide one or more protocol layers of a cellular wireless protocol to enable communication. For example, if the cellular wireless device 10000 is an eNodeB, the second transceiver 10040 provides functionality to implement the eNodeB. If the cellular wireless device 10000 is a UE, the second transceiver 10040 provides functionality to connect to a cellular network and transmit data over the network. The second transceiver 10040 may utilize the licensed bandwidth, but may also have circuitry to transmit and receive data over the unlicensed bandwidth.

The control circuit 10020 may control the first transceiver 10030 and the second transceiver 10040. When control circuit 10020 determines that an unlicensed channel is to be used for a cellular wireless protocol, control circuit 10020 may determine, using first transceiver 10030, when the channel is idle and, in some examples, reserve the channel using a channel reservation message via first transceiver 10030. Once the channel is idle, the control circuit 10020 can instruct the first transceiver 10030 or the second transceiver 10040 to transmit on the unlicensed frequency band using the cellular radio protocol.

In some examples, cellular wireless device 10000 can send a reservation message on an unlicensed channel. In some examples, the reservation message has a duration field that may be set to the duration of the cellular data transmission (e.g., a subframe). In some examples, cellular wireless device 10000 may not begin transmitting until a subframe boundary. In these examples, if a reservation message is sent, the duration of the reservation message may be equal to the duration of the cellular data transmission plus the amount of time until the next subframe boundary.

Fig. 11 illustrates a schematic diagram of an example wireless environment 11000, in accordance with some examples of the present disclosure. A cellular wireless device in the form of an eNodeB11010 provides cellular wireless communication for one or more cellular wireless devices in the form of UEs 11030. In some examples, the UE 11030 may utilize a cellular network provided by the eNodeB11010 to access a network, such as the internet 11060. The cellular wireless communication may be in accordance with one or more wireless standards, such as LTE. The

cellular wireless devices

11010 and 11030 may include the components of fig. 10 and 12 and implement any one or more of the methods or timelines shown in fig. 1-9.

Cellular wireless devices

11010 and 11030 may communicate on licensed or unlicensed frequencies. The wireless device 11050 (e.g., a laptop computer) may access one or more local area networks provided by the wireless device 11040 (e.g., an access point) that may operate in an unlicensed frequency. The wireless device 11050 may access a network, such as the internet 11060, through a wireless connection with the wireless device 11040.

Fig. 12 illustrates a block diagram of an example machine 12000 on which any one or more of the techniques (e.g., methods) discussed herein may be executed. In alternative embodiments, the machine 12000 may operate as a standalone device or may be connected (e.g., networked) to other machines. In a networked deployment, the machine 12000 may operate in the capacity of a server machine, a client machine, or both in server-client network environments. In one example, the machine 12000 may operate as a peer machine in a peer-to-peer (P2P) (or other distributed) network environment. The machine 12000 may be a cellular wireless device, a wireless device, or the like. Example cellular wireless devices include an eNodeB, a UE, a Personal Computer (PC), a tablet PC, a set-top box (STB), a Personal Digital Assistant (PDA), a mobile phone, a network appliance, a network router, switch or bridge, or any machine capable of executing instructions (sequential or otherwise) that specify actions to be taken by that machine. Further, while only a single machine is illustrated, the term "machine" shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein, such as a cloud computing configuration, a software as a service (SaaS) configuration, or other computer cluster configuration.

As described herein, an example may include, or may operate on, logic or multiple components, modules, circuits, or mechanisms. Modules and circuits are tangible entities (e.g., hardware) capable of performing specified operations and may be configured or arranged in a certain manner. In one example, a circuit may be arranged (e.g., internally or with respect to an external entity (e.g., other circuitry)) as a circuitry in a specified manner. In one example, all or a portion of one or more computer systems (e.g., a stand-alone computer system, a client computer system, or a server computer system) or one or more hardware processors may be configured by firmware or software (e.g., instructions, application portions, or applications) as circuitry that operates to perform specified operations.

Thus, the term "circuitry" is understood to include a tangible entity, whether physically constructed, specifically configured (e.g., hardwired), or temporarily (e.g., transitory) configured (e.g., programmed) to operate in a specified manner or to perform some or all of any of the operations described herein. Considering the example of temporarily configuring circuitry, each circuit need not be instantiated at any time. For example, where the circuitry includes a general purpose hardware processor configured using software, the general purpose hardware processor may be configured at different times as corresponding different circuitry. Thus, software may configure a hardware processor to, for example, form a particular circuit at one instance in time and form a different circuit at a different instance in time.

The machine (e.g., computer system) 12000 may include a hardware processor 12002 (e.g., a Central Processing Unit (CPU), a Graphics Processing Unit (GPU), a hardware processor core, or any combination thereof), a host memory 12001, and a static memory 12006, some or all of which may communicate with each other via an interconnect (e.g., bus) 12008. The machine 12000 may also include a display unit 12010, an alphanumeric input device 12012 (e.g., a keyboard), and a User Interface (UI) navigation device 12014 (e.g., a mouse). In one example, the display unit 12010, the alphanumeric input device 12012, and the UI navigation device 12014 may be touch screen displays. The machine 12000 may additionally include a storage device (e.g., drive unit) 12016, a signal generation device 12018 (e.g., a speaker), a network interface device 12020, and one or more sensors 12021 such as, for example, a Global Positioning System (GPS) sensor, compass, accelerometer, or other sensor. The machine 12000 may include an output controller 12028, such as a serial connection (e.g., Universal Serial Bus (USB)), a parallel connection, or other wired or wireless connection (e.g., Infrared (IR), Near Field Communication (NFC), etc.) to communicate with or control one or more peripheral devices (e.g., a printer, card reader, etc.).

The storage device 12016 may include a machine-readable medium 12022 on which is stored one or more sets of data structures or instructions 12024 (e.g., software), the data structures or instructions 12024 embodying or utilized by any one or more of the techniques or functions described herein. The instructions 12024 may also reside, completely or at least partially, within the main memory 12001, within static memory 12006, or within the hardware processor 12002 during execution thereof by the machine 12000. In an example, one or any combination of the hardware processor 12002, the main memory 12001, the static memory 12006, or the storage device 12016 may constitute machine-readable media.

While the machine-readable medium 12022 is shown to be a single medium, the term "machine-readable medium" can include a single medium or multiple media (e.g., a centralized or distributed database, and/or associated caches and servers) that are configured to store the one or more instructions 12024.

The term "machine-readable medium" may include any medium that is capable of storing, encoding or carrying instructions for execution by the machine 12000 and that cause the machine 12000 to perform any one or more of the techniques of the present disclosure, or that is capable of storing, encoding or carrying data structures used by or associated with such instructions. The machine-readable medium may include a non-transitory machine-readable medium. The machine-readable medium is not a transitory propagating signal. Non-limiting examples of machine-readable media may include solid-state memory, as well as optical and magnetic media. Specific examples of the machine-readable medium may include non-volatile memories such as semiconductor memory devices (e.g., electrically programmable read-only memories (EPROMs), electrically erasable programmable read-only memories (EEPROMs)) and flash memory devices; magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; random Access Memory (RAM); and CD-ROM and DVD-ROM disks. The instructions 12024 may also be provided through the use of a transmission mediumThe communication network 12026 transmits or receives data using any of a variety of transmission protocols (e.g., frame relay, Internet Protocol (IP), Transmission Control Protocol (TCP), User Datagram Protocol (UDP), hypertext transfer protocol (HTTP), etc.) via the network interface device 12020. Example communication networks may include a Local Area Network (LAN), a Wide Area Network (WAN), a packet data network (e.g., the internet), a mobile telephone network (e.g., a cellular network), a Plain Old Telephone (POTS) network, and a wireless data network (e.g., referred to as a "POTS") network

Of the IEEE802.11 family of standards, referred to as

IEEE 802.16 family of standards, IEEE 802.15.4 family of standards, and peer-to-peer (P2P) networks, etc. In one example, the network interface device 12020 may include one or more physical jacks (e.g., ethernet, coaxial, or phone jacks) or one or more antennas to connect to the communication network 12026.

In one example, the network interface device 12020 may include multiple antennas to wirelessly communicate using at least one of single-input multiple-output (SIMO), multiple-input multiple-output (MIMO), or multiple-input single-output (MISO) techniques. The term "transmission medium" shall be taken to include any intangible medium that is capable of storing, encoding or carrying instructions for execution by the machine 12000, and includes digital or analog communications signals or other intangible medium to facilitate communication of such software.

Other notes and examples

Example 1 includes a subject matter (e.g., an apparatus, device, or machine), comprising: a first transceiver to: transmitting and receiving in an unlicensed channel; a second transceiver to: transmitting and receiving in a grant channel and an unlicensed channel according to a cellular radio protocol; and a controller for: listen, via the first transceiver, for energy of an unlicensed channel over a predetermined number of one or more slots to determine that the unlicensed channel is unoccupied, the slots being defined with reference to timing information of a cellular wireless protocol, and in response to determining that the channel is unoccupied: scheduling, via a control channel transmitted on a grant channel, at least one User Equipment (UE) served by the eNodeB to receive data in a grant-free channel; and transmitting, via the second transceiver, data on an unlicensed channel starting at a cellular subframe boundary.

In example 2, the subject matter of example 1 can include, wherein the first transceiver is configured to: transmitting and receiving according to a non-cellular wireless protocol, and wherein the data transmitted on the unlicensed channel is a Supplemental Downlink (SDL) Physical Downlink Shared Channel (PDSCH), and wherein the controller is further configured to: transmitting, via the first transceiver, a wireless reservation message on an unlicensed channel to reserve the unlicensed channel for data transmitted on the unlicensed channel.

In example 3, the subject matter of any one of examples 1 to 2 can include, wherein the one or more slots are configured to: subdividing the plurality of samples in the current cellular subframe such that the one or more slots do not cross symbol boundaries in the current cellular subframe.

In example 4, the subject matter of any one of examples 1 to 3 can include, wherein at least one of the one or more slots is configured to: across the symbol boundary of the current cellular subframe.

In example 5, the subject matter of any of examples 1 to 4 can include, wherein the one or more slots are punctured from the current cellular subframe.

In example 6, the subject matter of any of examples 1 to 5 can include, wherein the cellular wireless protocol is a Long Term Evolution (LTE) or long term evolution-advanced (LTE-a) standards family defined by the third generation partnership project (3 GPP).

In example 7, the subject matter of any one of examples 1 to 6 can include, wherein the first transceiver is configured to: the transmission and reception are performed according to an Institute of Electrical and Electronics Engineers (IEEE)802.11 protocol.

In example 8, the subject matter of any one of examples 1 to 7 can include, wherein the controller is to: a fallback procedure is implemented and data is prohibited from being transmitted on the unlicensed channel until the fallback procedure is successful.

In example 9, the subject matter of any one of examples 1 to 8 may include, wherein the control channel is a Physical Downlink Control Channel (PDCCH), and wherein the controller is to: the predictive fallback procedure is to be completed before the end of the transmission of the PDCCH, and in response, the at least one User Equipment (UE) served by the eNodeB is scheduled to receive data on the unlicensed channel via the PDCCH transmitted on the licensed channel by the second transceiver before the fallback procedure is completed.

In example 10, the subject matter of any one of examples 1 to 9 can include, wherein the controller is to: determining that the fallback procedure is not completed before the end of the transmission of the PDCCH, and in response: ignoring hybrid automatic repeat request (HARQ) for data scheduled on an unlicensed channel; and informing the UE to clear the HARQ buffer for the data scheduled on the unlicensed channel.

In example 11, the subject matter of any one of examples 1 to 10 can include, wherein the second transceiver is configured to: the PDSCH is provided in a grant channel.

Example 12 includes a subject matter (e.g., an apparatus, device, or machine), comprising: listening on one or more slots for a secondary channel not specifically authorized for cellular wireless communication; determining that a received power of a secondary channel indicates that the secondary channel is idle during the one or more gaps; and in response: transmitting a reservation message on the secondary channel; scheduling at least one User Equipment (UE) to receive data on a Physical Downlink Shared Channel (PDSCH) transmitted on a secondary channel; communicating the schedule to the UE via a control channel on a primary channel that is authorized for cellular wireless communication; and transmitting the PDSCH on the secondary channel starting at the subframe boundary.

In example 13, the subject matter of example 12 can include wherein the one or more slots are defined with reference to timing information of a cellular wireless protocol.

In example 14, the subject matter of any of examples 12 to 13 may include wherein the instructions configure the eNodeB to: determining that a fallback procedure is to be completed after a current subframe and during a next subframe, the next subframe beginning at the subframe boundary; and in response to determining that the fallback procedure is to be completed after the current subframe and during a next subframe, scheduling the at least one UE on a Physical Downlink Control Channel (PDCCH) transmitted on the primary channel before completion of the fallback procedure.

In example 15, the subject matter of any of examples 12 to 14 may include wherein the instructions further configure the eNodeB to: the backoff procedure is successfully completed before the PDSCH is transmitted on the primary channel.

In example 16, the subject matter of any of examples 12 to 15 may include, wherein the instructions for the fallback procedure comprise instructions to: generating a random contention window; for each contention window, performing channel sensing for a second predetermined time period equal to the gap; and determining that the backoff procedure is successful by determining that, for each particular contention window, the received power during the particular contention window is below a predetermined threshold.

In example 17, the subject matter of any one of examples 12 to 16 may include, wherein the instructions for the fallback procedure comprise instructions to: the secondary channel is determined to be congested and, in response, the contention window is doubled.

Example 18 includes a subject matter (e.g., an apparatus, device, or machine), comprising: one or more processors configured to: determining that a power level of a first channel on one or more slots is below a first predetermined threshold, the first channel being a wireless channel not exclusively licensed for cellular wireless, and in response: selecting a random backoff window; determining that a power level of the first channel within the backoff window is below a second predetermined threshold; scheduling a User Equipment (UE) to receive data on a Supplemental Downlink (SDL) Physical Downlink Shared Channel (PDSCH) on the first channel using a control channel on a licensed second channel; and transmitting the SDL PDSCH on the first channel at a cellular subframe boundary in response to the power level of the first channel within the random backoff window being below the second threshold.

In example 19, the subject matter of example 18 can include wherein the one or more processors are configured to: providing a PDSCH on the second channel.

In example 20, the subject matter of any of examples 18 to 19 may include, wherein the one or more slots are aligned with respect to Long Term Evolution (LTE) or long term evolution-advanced (LTE-a) symbols.

In example 21, the subject matter of any of examples 18 to 20 can include wherein the symbol duration of the one or more slots is a consistent number of samples and is a factor of a number of samples in a Long Term Evolution (LTE) or long term evolution-advanced (LTE-a) subframe.

In example 22, the subject matter of any one of examples 18 to 21 may include, wherein the one or more processors are configured to: transmitting a wireless reservation message in response to determining that the power level of the first channel within the backoff window is below the second threshold.

In example 23, the subject matter of any of examples 18 to 22 may include, wherein the wireless reservation message is a clear-to-send (CTS) message, and wherein the CTS message has a duration field whose value is set to at least a time up to a cellular subframe boundary plus a time to transmit a PDSCH subframe.

In example 24, the subject matter of any one of examples 18 to 23 may include, wherein the one or more processors are configured to: determining that the power level of the first channel within the random backoff window is below the second threshold by being at least configured to determine that the received power is below the second threshold for each decrement of a random backoff window.

In example 25, the subject matter of any of examples 18 to 24 may include an antenna.

Example 26 includes subject matter (e.g., a method, means for performing an action, a machine-readable medium containing instructions that when executed by a machine cause the machine to perform the action, or cause an apparatus to perform) including: using one or more processors to: determining that a power level of a first channel on one or more slots is below a first predetermined threshold, the first channel being a wireless channel not exclusively licensed for cellular wireless, and in response: selecting a random backoff window; determining that a power level of the first channel within the backoff window is below a second predetermined threshold; scheduling a User Equipment (UE) to receive data on a Supplemental Downlink (SDL) Physical Downlink Shared Channel (PDSCH) on the first channel using a control channel on a licensed second channel; and transmitting the SDL PDSCH on the first channel at a cellular subframe boundary in response to the power level of the first channel within the random backoff window being below the second threshold.

In example 27, the subject matter of example 26 can include wherein the one or more processors are configured to: the PDSCH is provided on the second channel.

In example 28, the subject matter of any of examples 26 to 27 may include, wherein the one or more slots are aligned with respect to Long Term Evolution (LTE) or long term evolution-advanced (LTE-a) symbols.

In example 29, the subject matter of any of examples 26 to 28 may include, wherein the symbol duration of the one or more slots is a uniform number of samples and is a factor of a number of samples in a Long Term Evolution (LTE) or long term evolution-advanced (LTE-a) subframe.

In example 30, the subject matter of any one of examples 26 to 29 may include, wherein the one or more processors are configured to: transmitting a wireless reservation message in response to determining that the power level of the first channel within the backoff window is below the second threshold.

In example 31, the subject matter of any of examples 26 to 30 may include, wherein the wireless reservation message is a clear-to-send (CTS) message, and wherein the CTS message has a duration field whose value is set to at least a time up to a cellular subframe boundary plus a time to transmit a PDSCH subframe.

In example 32, the subject matter of any one of examples 26 to 31 may include, wherein the one or more processors are configured to: determining that the power level of the first channel within the random backoff window is below the second threshold by being at least configured to determine that the received power is below the second threshold for each decrement of a random backoff window.

Example 33 includes a subject matter (e.g., an apparatus, device, or machine), comprising: means for determining that a power level of a first channel on one or more slots is below a first predetermined threshold, the first channel being a wireless channel not exclusively licensed for cellular wireless, and in response: selecting a random backoff window; means for determining that a power level of the first channel within the backoff window is below a second predetermined threshold; means for scheduling a User Equipment (UE) to receive data on a Supplemental Downlink (SDL) Physical Downlink Shared Channel (PDSCH) on the first channel using a control channel on a licensed second channel; and means for transmitting an SDL PDSCH on the first channel at a cellular subframe boundary in response to the power level of the first channel within the random backoff window being below the second threshold.

In example 34, the subject matter of example 33 may include the means for providing the PDSCH on the second channel.

In example 35, the subject matter of any of examples 33 to 34 may include, wherein the one or more slots are aligned with respect to Long Term Evolution (LTE) or long term evolution-advanced (LTE-a) symbols.

In example 36, the subject matter of any of examples 33 to 35 can include wherein the symbol duration of the one or more slots is a uniform number of samples and is a factor of a number of samples in a Long Term Evolution (LTE) or long term evolution-advanced (LTE-a) subframe.

In example 37, the subject matter of any of examples 33 to 36 may include: means for transmitting a wireless reservation message in response to determining that the power level of the first channel within the backoff window is below the second threshold.

In example 38, the subject matter of any of examples 33 to 37 may include, wherein the wireless reservation message is a clear-to-send (CTS) message, and wherein the CTS message has a duration field whose value is set to at least a time up to a cellular subframe boundary plus a time to transmit a PDSCH subframe.

In example 39, the subject matter of any of examples 33 to 38 may include, wherein means for determining that the power level of the first channel within the random backoff window is below the second threshold comprises means for determining that the received power is below the second threshold for each decrement of the random backoff window.

Claims

1. An apparatus of an eNodeB, the apparatus comprising:

a memory; and

a processing circuit configured to:

listening for an unlicensed channel is idle for a first duration;

initializing a counter to a random number;

decrementing the counter each time the unlicensed channel is listened to be idle for at least a second duration defined relative to a time period of a cellular protocol of a licensed channel, until the counter is zero, if the listened unlicensed channel is idle for the first duration;

scheduling a User Equipment (UE) on a Physical Downlink Control Channel (PDCCH) to receive data on a Physical Downlink Shared Channel (PDSCH) transmitted in the license-exempt channel in response to determining that the counter is zero;

encoding a Physical Downlink Shared Channel (PDSCH) for transmission in the grant-free channel; and

in response to determining that the unlicensed channel is not idle for the second duration, again determining that the unlicensed channel is idle for the first duration, and in response thereto, continuing to listen for the unlicensed channel for the second duration.

2. The apparatus of claim 1, wherein the processing circuitry is to:

determining whether the unlicensed channel is idle by comparing a received power on the unlicensed channel to a threshold.

3. The apparatus of claim 1, wherein the first duration is defined relative to a time period of a cellular protocol of a grant channel and is selected such that there are a total number N of first duration time periods in a cellular subframe.

4. The apparatus of claim 3, wherein the first duration is N slots.

5. The apparatus of claim 1, wherein the processing circuitry is to:

transmitting a wireless reservation message on the unlicensed channel prior to transmitting the PDSCH.

6. An eNodeB, comprising:

transceiver circuitry comprising a processor to:

listening for an unlicensed channel is idle for a first duration;

in response to the unlicensed channel being sensed as idle during the first duration, setting a variable to a randomly generated value between a minimum value and a maximum value;

listening for the unlicensed channel for a predetermined duration, the predetermined duration being defined with reference to a cellular protocol operating on a licensed channel;

performing a determination of whether the unlicensed channel is idle for the predetermined duration, and in response to determining that the unlicensed channel is idle for the predetermined duration:

performing a determination of whether the variable is zero;

in response to determining that the variable is zero, transmitting a Physical Downlink Shared Channel (PDSCH) in the unlicensed channel; and

in response to determining that the variable is not zero, decrementing the variable, and repeating the operations of listening for the unlicensed channel and determining whether the unlicensed channel is idle until the variable is zero; and

in response to determining that the unlicensed channel is not idle for the predetermined duration, re-listening for the unlicensed channel for the first duration.

7. The eNodeB of claim 6, wherein the transceiver circuit is to:

8. The eNodeB of claim 6, wherein the transceiver circuit determines that the unlicensed channel is idle for the first duration, and in response to determining that the unlicensed channel is idle for the first duration, proceeds to:

performing a determination of whether the variable is zero;

in response to determining that the variable is not zero, decrementing the variable, and repeating the operations of listening for the unlicensed channel and determining whether the unlicensed channel is idle.

9. The eNodeB of claim 6, wherein the transceiver circuit determines that the unlicensed channel is not idle during the first duration, and in response thereto, listens to the unlicensed channel again for the first duration.

10. The eNodeB of claim 6, wherein the transceiver circuit is to schedule the UE on a Physical Downlink Control Channel (PDCCH) to receive data on a PDSCH transmitted in the license-exempt channel in response to determining that the variable is zero.

11. The eNodeB of claim 10, wherein the PDCCH is transmitted on the grant channel.

12. A machine-readable medium comprising instructions that when executed cause circuitry on an eNodeB to:

listening for an unlicensed channel is idle for a first duration;

initializing a counter to a random number;

decrementing the counter each time the unlicensed channel is sensed to be idle for at least a second duration, defined with reference to a cellular protocol operating on a licensed channel, until the counter is zero, in response to the unlicensed channel being sensed to be idle for the first duration;

in response to determining that the counter is zero, encoding a Physical Downlink Shared Channel (PDSCH) for transmission in the license-exempt channel; and

in response to determining that the unlicensed channel is not idle for the second duration, again determining whether the unlicensed channel is idle for the first duration before continuing to listen for the unlicensed channel for the second duration.

13. The machine-readable medium of claim 12, wherein the PDSCH is transmitted on a grant channel.

14. The machine-readable medium of claim 12, wherein the operations comprise operations to:

15. The machine-readable medium of claim 12, wherein the second duration is a gap.

16. The machine-readable medium of claim 15, wherein the slot is punctured from a current cellular subframe.

17. The machine-readable medium of claim 12, wherein the unlicensed channel is an industrial, scientific, and medical frequency band.